Various airway devices are known and are currently used in spontaneous breathing or IPPV to anaesthetise patients, or for resuscitation applications. The main focus of developments in such devices has heavily leaned towards ensuring the best shape and material combination to make such devices easy to insert and to improve sealing pressures once the device is in situ within the patient. This has been the case for both supraglottic devices which seal within the larynx and endotracheal tubes which seal within the trachea.
In particular in the case of supraglottic devices, the requirement for clinical knowledge and experience is invaluable in the decision-making process of choosing the correctly sized device for a given set of patient parameters. However, such decisions can still be very subjective and are arbitrarily related to the weight of the given patient, and will therefore be variable depending on the particular experience or preferences of individual clinicians. This increases the chance of selecting and using a device of the incorrect size for the given patient. Selecting an incorrectly sized device will lead to undesirable consequences, for example if a device that is too small for the patient is chosen this is likely to result in an over-insertion of the device beyond the larynx and deep into the trachea in the case of laryngeal airway devices, which can potentially result in traumatising and/or damaging the trachea, esophagus, vocal chords and upper esophagus in both human and animal patients.
The issues and consequences of incorrect device selection are particularly relevant in paediatric use. In pediatrics the stage of anatomical development is in a state of constant flux, with various rates of change from individual to individual, until adulthood is reached. When adulthood is reached the shapes of the internal anatomical structures become more stable and thus provide a more reliable environment for correct device size selection and use. Therefore, in pediatrics the risk of incorrect device size selection, which may result in over insertion or lack of optimal sealing forces of a device in the patient is much greater in pediatrics than in adults. This matter is highly exacerbated within veterinary anaesthesia situations as the anatomical parameters can vary significantly not only between species but also within a species type, such as in the case of dogs.
In addition to the problem of over-insertion of such supraglottic devices, another problem which can arise is accidental rotation of the device after insertion. This type of incident could result in the device being displaced from the correct sealing position within the human or animal patient. Some attempts have been made in the prior art to produce devices which do not readily succumb to rotation after insertion. This has been done by either widening the surface area of the device that is in contact with the top of the tongue or through the use of external fixation systems. However, such attempts have not been wholly successful in solving the rotation problem. In the case of external fixation this requires an additional effort on behalf of the clinician to secure the device and therefore unfortunately this is not always undertaken.
Yet another problem which still exists in present supraglottic devices, and in particular in airway type devices, is the possibility of the epiglottis of the human or animal patient down folding and occluding the airway within the device, thus blocking off the gas flow to and from the patient. The problem associated with down folding epiglottis is most applicable to paediatric and animal patients who have a large range in both the flexibility and size of the epiglottis.